Modular Assembly Having Press-Fit Fastener Holes

ABSTRACT

A modular assembly having a press-fit fastener hole. The press-fit fastener hole may include a plurality of lobe regions and a plurality of contact regions that may be spaced between lobe regions for a press-fit engagement with a fastener. The fastener may have a first diameter and the contact regions collectively may define an imaginary second diameter that is less than or equal to the first diameter.

Reference to Related Applications

This application claims priority to U.S. application Ser. No. 14/766,088filed on Aug. 5, 2015, which claims the benefit of U.S. Provisional Ser.No. 61/768,916 filed on Feb. 25, 2013, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to fasteners, and morespecifically, to fasteners that may be used to attach different modulesor sub-assemblies together, such as a vehicle oil pan to an engineblock.

BACKGROUND

In manufacturing industries, skilled artisans will appreciate that it issometimes desirable to partially assemble components to one anotherusing pre-positioned fasteners. This may enable further assembly at adifferent manufacturing location (e.g., even by a differentmanufacturer). Conventionally, pre-positioned fasteners include variousmechanical locking devices (e.g., split washers, nylon nuts, etc.),threadlocking material (e.g., commercially available Loctite™), orcaptive fasteners, just to name a few examples. However, theseconventional pre-positioned fasteners require extra materials havingextra weight and cost—and in some cases, may not retain the fastener'sposition, the fastener's orientation, or both.

SUMMARY

According to one embodiment, a modular assembly is provided having apress-fit fastener hole. The press-fit fastener hole includes aplurality of lobe regions; and a plurality of contact regions spacedbetween lobe regions for a press-fit engagement with a fastener having afirst diameter, the contact regions collectively defining an imaginarysecond diameter that is less than or equal to the first diameter.

According to another embodiment, a modular assembly configured to becoupled to another component is provided. The modular assembly includesa pan having a flange with at least one hole therethrough; and at leastone fastener press-fitted within the at least one hole. Each of the atleast one holes includes: a plurality of lobe regions, and a pluralityof contact regions, each contact region being located at an intersectionof two or more lobe regions, wherein the press-fit engagement of thefastener and the hole is associated with an inner diameter of the holeas defined by the contact regions and an outer diameter of the fastener.

DRAWINGS

Preferred exemplary embodiments will hereinafter be described inconjunction with the appended drawings, wherein like designations denotelike elements, and wherein:

FIG. 1 is an exploded perspective view of an engine assembly;

FIGS. 2A and 2B are top views of an exemplary press-fit fastener holethat may be used with the engine assembly of FIG. 1;

FIGS. 3A-3C are side views of a fastener, in this case a bolt, beinginstalled in the exemplary press-fit fastener hole of FIGS. 2A and 2B,where in FIG. 3A the fastener is not yet installed, in FIG. 3B thefastener is partially installed, and in FIG. 3C the fastener iscompletely installed;

FIG. 3D is a cross-sectional view of the fastener of FIG. 3B;

FIG. 4 is a flowchart illustrating an exemplary method for providing amodular assembly with fasteners pre-installed in press-fit fastenerholes;

FIG. 5A is a side view of a fastener and spacer being installed inanother exemplary press-fit fastener hole, where the spacer andpress-fit fastener hole work together to retain the fastener in place;

FIG. 5B is a partial, cross-sectional view of the fastener, spacer, andpress-fit fastener hole of FIG. 5A fully installed in an engineassembly;

FIG. 5C is a top view of the spacer shown in FIG. 5A;

FIGS. 6-11 are top views of other exemplary press-fit fastener holes;

FIG. 12A is a side view of a fastener and another spacer being installedin another exemplary press-fit fastener hole, where the spacer andpress-fit fastener hole work together to retain the fastener in place;

FIG. 12B is a partial, cross-sectional view of the fastener, spacer, andpress-fit fastener hole of FIG. 12A fully installed in an engineassembly; and

FIG. 12C is a top view of the spacer shown in FIG. 12A.

DETAILED DESCRIPTION

Manufacturers today oftentimes require their suppliers to provide themwith parts in the form of modules or sub-assemblies (hereafter referredto as modular assemblies), which the manufacturer may then combine withother parts so as to form a larger assembly or even a finished product.In some circumstances, it is desirable for the supplier to provide themodular assembly with fasteners (e.g., bolts, screws, etc.) already inplace, so that the manufacturer can simply line up the modular assemblywith another part and attach them together with the already providedfasteners. Consider the exemplary engine assembly 10 illustrated in FIG.1, where an oil pan 12 is provided by a supplier with a number offasteners 14 already installed and aligned in their respective holes sothat the oil pan can be quickly and easily attached to an engine block16. By receiving the oil pan 12 with the pre-installed fasteners 14already inserted into the correct holes and ready for attachment, themanufacturer is able to more quickly and efficiently mount the oil pan12 to the engine block 16. The manufacturer does not, for example, haveto maintain its own inventory of bolts, nor does it have to take thetime to retrieve a bolt from a storage bin, insert the bolt through theappropriate hole, and align the bolt so that it will mate with acorresponding mounting hole in the engine block bolt pattern. Onechallenge associated with providing modular assemblies, like the oil pan12, with fasteners already in place is that, without any feature to thecontrary, the fastener or bolt can simply fall out of the hole in themodular assembly or otherwise become misaligned. The press-fit fastenerholes described herein are designed to address this challenge.

Engine assembly 10 includes a modular assembly (e.g., an oil pan 12), anengine block 16, and an intervening gasket 18. The oil pan 12 isattached to the underside of the engine block 16 with a number ofpre-installed fasteners 14 that are already retained and aligned inpress-fit fastener holes 30 located around the perimeter of the oil pan,such as in a mounting flange 32. These fasteners 14 thread intocorresponding holes 38 in an engine block mounting flange 36. A thin,complementary shaped gasket 18 is compressed between the oil pan 12 andthe engine block 16 and seals a sump 34 located between those two parts,as is widely understood in the art. It should be appreciated that engineassembly 10 is only one potential application or use of the press-fitfastener holes described herein, as they may be used in any application(automotive or non-automotive) where it is desirable to provide amodular assembly with pre-installed fasteners so that the modularassembly can be more easily attached to other parts. Some non-limitingexamples of other applications where press-fit fastener holes may beused include: transmission pans and timing belt, chain, gear, cam and/orvalve covers; thus, the term pan should be construed broadly to includeany suitable type of pan, cover, sump, lid, etc.

Turning now to FIGS. 2A and 2B, the press-fit fastener hole 30 isdesigned to retain fasteners 14 in place via an interference fit (orpress or friction fit) so that when the oil pan is received by amanufacturer from a supplier it is pre-assembled and ready forattachment to the engine block 16. As better shown in FIGS. 2A and 2B,the press-fit hole 30 may be a multi-lobal hole with at least threepoints or regions of contact or engagement 60 (e.g., 60 a, 60 b, 60 c)so that the hole can provide an interference or press-fit engagementwith a fastener 14 that is inserted therein. In the illustratedembodiment, the contact regions 60 a, 60 b, 60 c are cusps, however, aswill be explained below, this is merely one embodiment. The contactregions may both retain the position of the fastener (i.e., prevent thebolt from simply falling out of the oil pan) and retain the alignment ororientation of the fastener (i.e., keep the bolt straight or aligned sothat it is properly oriented for insertion through holes 40 and 38). Thefollowing description is directed to an embodiment where an oil pan 12is provided with a number of fasteners 14 already pre-installed, but itis also possible to provide an oil pan/gasket combination with fasteners14 pre-installed. For example, it is possible for the compressionlimiter holes 40 in gasket 18 to be press-fit fastener holes. In thislatter embodiment, the fasteners 14 may be used to maintain the oil pan12 and gasket 18 together while they are shipped from the supplier tothe manufacturer.

In the exemplary embodiment shown in FIG. 2A, the fastener hole 30 maybe tri-lobular—i.e., having a shape defined by three lobe regions 62(e.g., 62 a, 62 b, 62 c). The lobe regions 62 may be adjacent to oneanother, and along an interior surface 64 of the hole 30, each loberegion may meet at contact regions 60 (e.g., the cusps each having aradially, inwardly directed point or index). In one embodiment, thecontact regions 60 define an imaginary circular, inner diameter D_(3A)(e.g., from about 6 mm-10 mm) which corresponds to the diameter of thefastener, and the lobe regions 62 are circumscribed within an imaginarycircular, outer diameter D_(3B) (e.g., from about 8 mm-12 mm). In oneparticular embodiment shown in FIG. 2B, the shape of the tri-lobularhole may be defined by three overlapping circles (a, b, c), and some ofthe points where the circles a, b, and c intersect may coincide with thecontact regions 60. It is possible for the diameter of at least one ofthe circles a, b, and c (e.g., respective diameters D_(3a), D_(3b), orD_(3c)) to be equal to the inner diameter D_(3A) of the fastener hole,or in another embodiment the diameter of all the circles a, b, and c maybe equal to or within 5% of the diameter D_(3A) (e.g.,D_(3A)=D_(3a)=D_(3b)=D_(3c)). Further, it is not necessary that the loberegions 62 be circular, as they could be oval or some other suitableshape.

As shown in FIG. 3A, the fastener 14 which is to be received in thepress-fit fastener hole 30 is an attachment feature, such as a bolt or ascrew, that is used to securely mount the oil pan 12 and gasket 18 tothe underside of the engine block 16. In the illustrated embodiment,fastener 14 is a bolt and includes a head portion 80 coupled to athreaded shank portion 82 which extends axially therefrom. The headportion 80 can be larger in diameter than the shank portion 82 so thatit does not pass through the hole in which the fastener is inserted and,depending on the particular application, can include any number ofengagement features. In the hex bolt example illustrated in FIGS. 3A-3D,the head portion 80 has a hex configuration for engagement by a wrenchor the like, but it may alternatively be configured as a carriage bolt,shoulder bolt, lag bolt, lug bolt, head bolt, machine screw, socketscrew, set screw, or any other type of suitable fastener.

The shank portion 82 is an elongated shank or shaft that axially extendsaway from the head portion 80 and, according to this example, includesthreaded section 84 and a pilot section 86. The exterior or male threads88 of the threaded section 84 are designed to interact with interior orfemale threads in the mounting holes 38 in the engine block boltpattern, as illustrated in FIG. 3C, but this is not necessary as it isalso possible for the threaded section 84 to interact with a nut or someother fastening device. The threaded section 84 of the fastener has anouter diameter (OD_(F)) that may, by way of example, be between about 6mm and 10 mm. In one exemplary embodiment, the outer diameter OD_(F) is1-10% larger than the inner diameter D_(3A) defined by the contactregions 60 of the tri-lobular hole 30. The pilot section 86, which isoptional, has a smooth exterior surface that is smaller in diameter thanthe threaded section and is intended to help guide the tip of thefastener 14 into the hole in which it is being inserted. In otherembodiments, the shank portion 82 does not include a pilot section andis threaded all the way to its distal end. The fastener 14 can beinstalled to either a threaded blind or through hole in the matingcomponent.

The fastener 14 may have various sizes, dimensions, configurations,material compositions, etc. and may be any type of known bolt, screw orthe like. For example, the length, the thread count, the threads perinch (TPI), the pitch, the lead, the units (Metric or English), the heador shank portion configuration, or any other suitable parameter may varyaccording to the particular application in which the fastener 14 isbeing used. Although the fastener described herein is not limited to anyone type of fastener or bolt, the exemplary fastener 14 is an M6 or M8bolt. Fastener 14 may be made of various metals (or metal alloys),plastics, or even ceramics, and the fastener may or may not be coated(e.g., zinc plating, galvanizing, chrome plating, etc.), to cite a fewexamples.

In order for the interference fit to adequately retain the fastener 14in the press-fit fastener hole 30 (and adequately retain its alignment),the engagement between the contact regions 60 and the threads 88 of thefastener 14 should adequately support the weight of the fastener 14 onceit is located within the hole 30; if it does not, the bolt could simplyfall back through the hole (e.g., at the time of engagement or laterduring shipment). Conversely, the engagement between the contact regions60 and the threads 88 should not be so great as to prevent the bolt frombeing later fully installed or threaded into the hole 38 of the engineblock; e.g., the interference fit between the bolt and the contactregions should not be so great as to damage the threads 88 in such a waythat the threads fail to engage the female threads within the engineblock hole 38. Also, the engagement should not be so excessive so as toproduce high or faulty bolt torque readings at installation. In someembodiments, this engagement should be sufficient to retain a relativelyperpendicular alignment of the fastener to the mounting flange 32 sothat the manufacturer later does not need to carry out an additionalalignment step. In one example, the engagement between the contactregions 60 and the threads 88 of the fastener 14 may result in anangular displacement or misalignment of the bolt (i.e., the anglebetween a line perpendicular to the surface of the gasket 18 and thecentral axis of the bolt) that is less than or equal to about 5°; insome instances, it may be less than or equal to 1°. If the angularmisalignment is greater than this, the bolt may not line up properlywith the corresponding hole 40 in the gasket and the engine block hole38. In another embodiment (not shown), the contact regions 60 may havefemale threads thereon sized to receive the fastener threads 88, and thefastener may be rotated into the press-fit fastener hole 30.

FIG. 4 illustrates an exemplary method 100 for providing a modularassembly, in this case an oil pan, from a supplier to a manufacturerwhere the modular assembly already has one or more pre-installedfasteners 14. Starting with step 101, the supplier receives or maintainsa collection of fasteners 14; in this case threaded bolts. Next, thesupplier inserts or installs the fasteners 14 into the press-fitfastener holes 30 of a module by press-fitting them therethrough,creating a modular assembly (step 102). In this example, the holes 30are located in the oil pan mounting flange 32 and the fasteners 14 areinserted to a predetermined depth within the holes. This step may beperformed manually or it may be automated with manufacturing equipment.When installing a fastener 14 into a press-fit fastener hole 30, thefastener should be inserted far enough into the hole such that thethreads 88 engage each of the contact regions 60. This installation ofthe fastener 14 into the press-fit fastener hole 30 may automaticallyalign the bolt in an upright and aligned orientation, or the bolt mayneed to be manipulated so that it is properly aligned. Again, manual orautomated means may be used for carrying this out. At this point, thegasket 18 may or may not be provided with the oil pan 12 (e.g.,press-fitting the fasteners 14 into the holes 40).

After the various fasteners 14 have been installed in their respectiveholes, the modular assembly with its pre-installed fasteners may beshipped or otherwise provided to the manufacturer for subsequentassembly operations (step 103). The manufacturer may then attach the oilpan 12 and gasket 18 to the underside of the engine block 16, asdescribed above, and can do so in a more efficient manner due to thefasteners or bolts being already installed, aligned and ready to go.

It should be appreciated that the illustrated engine block, gasket, oilpan, and fasteners are provided only by way of example. The engine blockmay be any other component or assembly. The oil pan may be various otherpans, covers, trays, plates, modular assemblies, etc. And the fastenermay also vary as previously described.

Other embodiments of the modular assembly, fastener and/or press-fitfastener holes also exist. In the illustrated examples that follow, likereference numerals indicate like or similar elements or functions.

For example, FIGS. 5A-5C show a fastener 114 and a spacer 120 that maybe used for improved alignment of the fastener or bolt. In theembodiment shown, the spacer 120 is a generally hollow cylinder having afirst outer diameter OD_(S1) (which may be less than, greater than, orequal to the diameter of the head portion 180 of the fastener; here, itis illustrated as being approximately equal to the diameter of the headportion). A first end 122 of the spacer may be nearest the head portion180 while a second end 124 may be furthest away from the head portion.The outer diameter OD_(S2) of the second end 124 may be smaller thanthat of the first end 122, having a shoulder 126 therebetween (i.e.,OD_(S2)<OD_(S1)). Multiple gaps 128 may extend axially from the secondend 124 towards the shoulder 126 (e.g., the three illustrated gaps maycorrespond with the contact regions 60 in the hole 30) (see also FIG.5C). The second outer diameter OD_(S2) may be sized to fit within thepress-fit fastener hole 30 in the oil pan mounting flange 32 while thegaps 128 are co-located around the contact regions 60 so that the secondend 124 does not interfere with the press fitting of the fastener 114 inthe hole 30. In some instances, the second end 124 of the spacer mayalso be press-fit into the lobe regions 62 of the hole duringinstallation. An inner diameter IDs of the spacer should be large enoughso that the spacer can fit over top of the shank portion 182 of thefastener 114.

FIG. 5B is similar to FIG. 3C in that it illustrates the fastener withthe spacer 120 fully installed in the engine block 16 securing the oilpan 12 and gasket 18 therebetween. It also illustrates the second outerdiameter OD_(S2) within the press-fit fastener hole 30 and the shoulder126 mated or resting against the flange 32 near the hole 30. This nestedrelationship may improve the alignment of bolt 114 so that it is moreupright, and the spacer 120 may be retained during final installationinto the engine block (FIG. 5B) so that the manufacturer does not haveto perform an additional step of removing the spacer 120.

In another spacer embodiment shown in FIGS. 12A-12B, the spacer's innerdiameter may have a multi-lobular arrangement, similar to that shown inFIGS. 2A and 2B. For example, the inner diameter may have lobes 62 a, 62b, 62 c and contact regions 60 a, 60 b, 60 c. Similarly, the diameterD_(3A) may be suitably sized for a press-fit engagement with the threadsof the fastener 182. In this implementation, the second end 124 may becontinuously circular; i.e., it may not have gaps 128 (as described withrespect to FIGS. 5A-5C). Furthermore, the holes 30′ in the flange 32 maybe circular and sized to receive the second end 124′ of the spacer 120′.In addition, when the spacer is installed into the flange 32, the secondend 124′ may be clinched or coined into place, as understood by skilledartisans. Thus, a portion of the second end 124′ may be folded over theopposing side of the flange 32, as shown in FIG. 12A. Of course, meansfor securing the spacer 120′ are possible as well—includingpress-fitting the spacer into the hole 30′.

In the implementations shown in FIGS. 5A-5C and 12A-12C, the spacer mayimprove the grip length of the bolt thereby improving alignment as theaxial length of the spacer (120, 120′) may be greater than axial depthof the flange 32. Further, when the oil pan 12 is assembled to theengine block 16, spacer implementations place the fastener 182 intension thereby enhancing the clamping force on the pan. The spacers maybe composed of any suitable material including metal(s) or plastic(s).

In another spacer embodiment shown in FIG. 6, a spacer 620 may have anyshape (e.g., circular); and the hole in the mounting flange may have acomplementary shape (e.g., circular). The outer diameter of the spacernear the second end 624 may be slightly larger than the diameter of themounting flange hole so that the spacer may be press-fit therein. Whilethe spacer 620 may be generally cylindrically hollow therethrough, theinterior surface 644 of the spacer may have axially extendingprojections which each extend radially inwardly to a tip or contactregion 660. The contact regions 660 may define the diameter D_(3A) whichis slightly smaller than the fastener so that the fastener may be pressfit therethrough once the spacer 620 is installed in the mountingflange.

In other embodiments, the press-fit fastening holes may have differentshapes. And in some instances, the contact regions 60 may be flat ratherthan angular cusps. For example, in one embodiment shown in FIG. 7, thefastening hole 730 may be triangular and have contact regions 760. Or,for example in FIG. 8, the contact regions 860 may have indexes or tipsor projections (e.g., indexes extending from a circular hole 830 in themounting flange). In other embodiments, the number of contact regionsmay vary; e.g., there may be four, five, six, or more contact regions.In FIG. 9, four contact regions 960 are illustrated and the hole 930 issquare. In FIG. 10, five contact regions 1060 are illustrated and thehole 1030 is star-shaped. And in FIG. 11, six contact regions 1160 areillustrated and the hole 1130 is hexagonal. Thus, as shown in FIGS.7-11, the lobe regions need not be circular, but may have various shapesand sizes.

Other embodiments may also exist. For example, additional annularretention and alignment features made from low density foam or othersuitable materials may be inserted around the bolt to assist withretaining and aligning the bolt within the hole, as described in U.S.patent application Ser. No. 61/807,008 which is hereby incorporated byreference in its entirety.

It is to be understood that the foregoing description is not adefinition of the invention, but is a description of one or morepreferred exemplary embodiments of the invention. The invention is notlimited to the particular embodiment(s) disclosed herein, but rather isdefined solely by the claims below. Furthermore, the statementscontained in the foregoing description relate to particular embodimentsand are not to be construed as limitations on the scope of the inventionor on the definition of terms used in the claims, except where a term orphrase is expressly defined above. Various other embodiments and variouschanges and modifications to the disclosed embodiment(s) will becomeapparent to those skilled in the art. All such other embodiments,changes, and modifications are intended to come within the scope of theappended claims.

As used in this specification and claims, the terms “for example,”“e.g.,” “for instance,” “such as,” and “like,” and the verbs“comprising,” “having,” “including,” and their other verb forms, whenused in conjunction with a listing of one or more components or otheritems, are each to be construed as open-ended, meaning that the listingis not to be considered as excluding other, additional components oritems. Other terms are to be construed using their broadest reasonablemeaning unless they are used in a context that requires a differentinterpretation.

1. A modular assembly having a press-fit fastener hole, the modularassembly comprising: a flange defining an aperture; and a spacerreceived within the aperture, the spacer defining the press-fit fastenerhole within the aperture in the flange, the press-fit fastener holeincluding: a plurality of lobe regions; and a plurality of contactregions spaced between lobe regions for a press-fit engagement with afastener having a first diameter, the contact regions collectivelydefining an imaginary second diameter that is less than or equal to thefirst diameter; wherein the spacer defines a shoulder configured tospace a head of the fastener away from the flange.
 2. The modularassembly of claim 1, wherein the press-fit fastener hole has three loberegions, the lobe regions defined by three overlapping ellipses.
 3. Themodular assembly of claim 1, wherein each of the contact regions includea cusp.
 4. The modular assembly of claim 1, further comprising thefastener having a shank with the first diameter, wherein the shank isslidably received in the press-fit fastener hole, wherein when the shankis located in the press-fit fastener hole, the position and orientationof the fastener are retained.
 5. The modular assembly of claim 4,wherein the fastener shank has a plurality of male threads along itsaxial length engaging the contact regions, wherein the male threads areadapted to be both press-fit against the contact regions and afterwardsbe received by female threads.
 6. The modular assembly of claim 4,wherein the first diameter is 1-10% larger than the imaginary seconddiameter.
 7. The modular assembly of claim 4, wherein the orientation ofthe fastener shank with respect to the flange is retained within a 5degree angle between a line perpendicular to a surface of the flange andthe longitudinal axis of the fastener.
 8. The modular assembly of claim4, further comprising a pan comprising the flange, wherein the pan isone of an oil pan, a transmission pan, a timing belt cover, a chaincover, a gear cover, a cam cover, or a valve cover.
 9. The modularassembly of claim 1, wherein when the fastener is located in thepress-fit fastener hole of the spacer, the position and orientation ofthe fastener with respect to the flange are retained.
 10. The modularassembly of claim 1, wherein the spacer is formed from a plasticmaterial.
 11. A modular assembly configured to be coupled to anothercomponent, comprising: a pan having a flange, a flange having anaperture receiving a spacer therein, the spacer with at least one holetherethrough, the at least one hole extending through the aperture ofthe flange; and at least one fastener press-fitted within the at leastone hole, the fastener having a head contacting a shoulder of thespacer, such that the head of the fastener is spaced away from theflange by the shoulder, wherein each of the at least one holes includes:a plurality of lobe regions, and a plurality of contact regions, eachcontact region being located at an intersection of two or more loberegions, wherein the press-fit engagement of the fastener and the holeis associated with an inner diameter of the hole as defined by thecontact regions and an outer diameter of the fastener.
 12. The modularassembly of claim 11, wherein the contact regions are radially inwardlyextending cusps.
 13. The modular assembly of claim 11, wherein theshoulder contacts the head of the fastener such that the shouldermaintains an alignment of the head, wherein the at least one fastener isconfigured for position and orientation retention within the hole untilthe modular assembly is fixedly coupled to said another component viathe at least one fastener.
 14. The modular assembly of claim 13, whereinthe orientation of a longitudinal axis of the fastener is retained withrespect to the flange within a 5 degree angle between a lineperpendicular to a surface of the flange and a central axis of thefastener.
 15. The modular assembly of claim 11, wherein the spacer isformed from a plastic material.